Fish tacos

Name: Fish tacos
Prep time: 30 min
Cook time: 30 min
Total time: 1 h
Cuisine: Mexican
Ingredients: 1 small red onion, peeled, halved and sliced into half moons; 2 limes, juice only; 125g/4½oz mayonnaise; 2 tsp gochujang paste, or other hot sauce, to taste; 1 x 198g/7oz tin sweetcorn, drained; 1 fresh red chilli, finely diced (de-seed if you don’t like too much heat); 3 tbsp chopped fresh coriander; salt, to taste; 4 skinless fillets of firm white fish, such as hake or haddock (750–900g/1lb10oz-2lb total), from the thicker loin end; 1 tsp ground cumin; ½ tsp paprika; 1 tsp sea salt flakes; 1 garlic clove, peeled and finely grated or minced; 2 tbsp regular olive oil; 8 soft corn tortillas; 2 ripe avocados; 1 lime, juice only, plus 2 limes, cut into wedges; salad leaves of your choice; 1–2 tbsp chopped fresh coriander